Knowledge of amino acid metabolism is critical to human health and has significant industrial applications as well. This study proposes to develop a coproduct method for the production of L-lysine, an essential amino acid of great economic and industrial importance. If successful, the L-lysine produced as a result of this study will be a coproduct of the erythromycin fermentation using Saccharopolyspora erythraea. Currently, L-lysine is produced from dedicated Corynebactium glutamicum fermentations, and as such, has costs associated with its production that are not absorbed through the production of a primary fermentation product. L-lysine produced as a coproduct from the erythromycin fermentation would be substantially less expensive to produce, and large quantities could be produced using this method because the erythromycin fermentation is also a very large-scale process. In addition, this study also proposes to investigate the potential for developing a dedicated fermentation method for L-cysteine production, using an erythromycin non-producing variant of S. erythraea. Until recently there was no need for fermentation-produced L-cysteine;but due to recent government regulations against the use of animal derived L-cysteine, the market for fermentation-produced material has grown significantly. The model organism used in this study is the erythromycin producing organism, S. erythraea, a bacterium that has been the subject of over 50 years of intensive genetic and biochemical research, providing a solid foundation upon which to build commercial processes for amino acid production. Public Health Relevance: Prion diseases, or transmissible spongiform encephalopathies (TSEs), are a family of rare progressive neurodegenerative disorders that affect both humans and animals. Prion diseases are usually rapidly progressive and always fatal. This project aims to reduce the risk of acquiring TSE<s in the population through the development of a biotechnological process for the production of amino acids that are used by humans and are currently obtained from possibly contaminated animal sources.